1. Field of the Invention
The present invention relates to a steer by wire apparatus. More particularly, the present invention relates to a steer by wire apparatus which controls a steering angle by converting a vertical rotation caused by a motor into a horizontal rotation.
2. Description of Related Art
Generally, a steering apparatus is an apparatus for controlling a moving direction of a vehicle. A driver rotates a steering wheel so as to change the moving direction to his intention. Such a steering apparatus is an important means for the driver to drive and control the vehicle.
According to the steering apparatus, if the driver rotates the steering wheel, torque generated by the rotation of the steering wheel is applied to a wheel.
Recently, a steer by wire (SBW) apparatus is used for steering a front wheel between the steering wheel and the front wheel.
Such a steer by wire apparatus includes a steering wheel which a driver directly handles for steering, a reaction motor mounted at one side of the steering wheel and supplying reaction torque according to a rotation of the steering wheel, an actuator connected to a tie rod and performing a steering operation, a sensing means detecting a change of torque, a steering angle, and a vehicle speed according to the rotation of the steering wheel, and an ECU operating the actuator and the reaction motor according to an electrical signal transmitted from the sensing means.
FIG. 5 is a schematic diagram showing movements of a tie rod according to a conventional steer by wire apparatus. As shown in FIG. 5, a tie rod 3 is moved by operating L-shape levers 1 pivoted at a point P1 through an actuator (not shown) according to a conventional steer by wire apparatus.
If the actuator inputs reciprocal motions to the L-shape lever 1, the L-shape lever 1 pivots about the point P1 and makes a tie rod inner point T1 move to the left or to the right. Thereby, a steering angle of the wheel W is controlled.
According to a conventional SBW mechanism different from a conventional rack and pinion mechanism, the tie rod inner point T1 moves forward or rearward as well as to the left or to the right. Therefore, geometry characteristic of the tie rod may change.
In addition, the L-shape levers 1 and the tie rod 3 are operated only by the actuator when steering the wheel. Therefore, performance on demand of the actuator and cost may increase. In addition, since an external force is transmitted to the actuator through the wheel, load and usage of current may increase.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.